Law enforcement officers gather near the scene where the body of a woman was found near Interstate 35 north of Laredo, Texas, on Saturday.

A US Border Patrol agent suspected of killing four women was arrested Saturday after a fifth woman escaped and notified law enforcement, who referred to the agent as a "serial killer."

Juan David Ortiz, a supervisor for the Border Patrol, was arrested by the Texas Rangers early Saturday morning in relation to multiple homicides in and around Laredo, Texas.

Webb County Sheriff Martin Cuellar confirmed in a statement that the 35-year-old had murdered the four victims within the past two weeks. Ortiz, a Navy veteran, had been with the US Customs and Border Protection agency for 10 years.

Webb County Sheriff's Office

Webb County District Attorney Isidro Alaniz described Ortiz as a "serial killer" who preyed on sex workers whom he picked up at bus stops and parking lots in the Laredo area. In the last two weeks, Alaniz said, Ortiz killed four women, one of whom was transgender.

"He would take these women out to desolate highway areas, and once he got them there he would take them out of his truck and execute them," Alaniz told BuzzFeed News.

All of the victims were shot in the head — some in the face — with a handgun, Alaniz said. Ortiz is suspected of killing the four women while he was off duty. Investigators do not yet know if he used a service weapon in the killings.

Two of the victims were identified as Melissa Ramirez and Claudine Ann Luera. The other two have not been identified.

The fifth victim, who was able to escape from Ortiz, said he took her to his house and began to act "weird" when she started to talk about one of the other women he allegedly killed, whose body had been found the week before, according to the criminal complaint.

Ortiz and the woman left his house in his pickup truck and stopped at a gas station that was three or four blocks from a Border Patrol station, Alaniz said.

The fifth victim then again brought up the woman who had been killed, and that's when Ortiz pulled out a black pistol and pointed it at her, according to the complaint.

According to the document, Ortiz tried to prevent her from exiting the truck, grabbing her shirt, but the woman pulled the shirt off and ran away from the moving vehicle, toward a state trooper, whom she asked for help.

About an hour later, state troopers located the truck and tried to question Ortiz, who ran to a multilevel hotel parking garage. He was eventually found hiding in the bed of a truck, Alaniz said.

Prosecutors said that after the woman escaped, Ortiz, a married man with children, picked up a Jane Doe in Laredo. The Border Patrol agent drove her out of the city limits on Interstate 35 and told her to exit at mile marker 20. He shot her in the head multiple times before driving back to Laredo.

That same night, Sept. 15, Ortiz picked up another victim and again drove them out of the city limits. He told them to exit his truck at mile marker 15 and shot them in the back of the head. Ortiz, who confessed to the Texas Rangers, told authorities the body was behind gravel pits. Webb County deputies found the body and a single bullet casing.

Ortiz, a Navy veteran, admitted to killing the four women between Sept. 3 and Sept. 15, the district attorney said. He added that there was no indication Ortiz had murdered additional women.

"They did not deserve to die the way they did," Alaniz said of the victims.

Ortiz was charged with second-degree aggravated assault with a deadly weapon, third-degree unlawful restraint, and four counts of first-degree murder.

"We want to reassure the citizens of Laredo that the community and your families are safe," the Laredo police, which had been assisting in the investigation, said in a statement Saturday.

In a statement, CBP spokesperson Andrew Meehan said that the agency was assisting in the investigation into Ortiz, and that the Department of Homeland Security's inspector general had been notified.

"Our sincerest condolences go out to the victims’ family and friends. While it is CBP policy to not comment on the details of an ongoing investigation, criminal action by our employees is not, and will not be tolerated," Meehan said. "Out of respect to the victims’ family and friends, we ask that deference and due process be given to the investigation so that all the facts are brought to light and they can receive the closure they deserve.”

Ortiz is the second Border Patrol agent from the Laredo sector accused of multiple murders this year. Ronald Burgos-Aviles, a 28-year-old Border Patrol agent, was arrested in April on two counts of capital murder, after reporting that he found the bodies of his girlfriend, 27-year-old Grizelda Hernandez, and her 1-year-old son Dominick Hernandez near a park in South Texas.

Ortiz joined CBP in 2008, amid a relaxation of hiring standards aimed at boosting the agency's ranks. In congressional testimony in 2015, Gil Kerlikowske, then the head of CBP, said that the rush to double the number of Border Patrol agents after the 9/11 terrorist attacks had allowed bad actors to join the agency's forces.

"When we lowered our standards of hiring and did not properly vet people, we made mistakes in who got hired. And we paid a price for that and are continuing to pay a price for that,” Kerlikowske told the House of Representatives’ Appropriations Committee at the time.

Adolfo Flores is a national security correspondent for BuzzFeed News and is based in Los Angeles. He focuses on immigration.